Smudge-resistant pressure-sensitive transfer sheet and method of making



1962 D. A. NEWMAN ET AL 3,017,297

SMUDGERESISTANT PRESSURE-SENSITIVE TRANSFER SHEET AND METHOD OF MAKINGOriginal Filed Oct. 11, 1957 ADHESIVE 1 7 LAYER TRANSFER H420 LOWwuss/v5 P/G'M'ENT LAYEZ J] FOUNDAT/UA/ 2 IMAGE HARD, Law ADHESIVE 5dP/GMENT LAYER.

ADl-IEZSIVE 74 LAYER copy SHEE' INVENTORS Douglas A.Newrr7arz gfaroldEEC Dixon ATTORNEY? United States atent SMUDGE RESISTANT PRESSURESENSITIVE TRANSFER SHEET AND METHOD OF MAKING Douglas A. Newman, GlenCove, and Harold F. E. Dixon, Douglaston, N.Y., assignors to ColumbiaRibbon & Carbon Manufacturing Company, Inc., Glen Cove, N.Y.. acorporation of New York Original application Oct. 11, 1957, Ser. No.689,635, now Patent No. 2,912,344, dated Nov. 10, 1959. Divided and thisapplication Sept. 9, 1959, Ser. No. 838,921

13 Claims. (Cl. 117216) This invention relates to transfer writing andparticularly to the placing of marks and indicia by means of printing orwriting pressure or a type blow, acting through a pressure-sensitivetransfer sheet of the carbon paper type.

The present application is a division of application Serial No. 689,635filed October 11, 1957, now Patent No. 2,912,344 granted November 10,1959.

Transfer sheets of the carbon paper type have, of course, been known andused for many years. Lately, however, the placing of various types ofrecord marks on copy sheets or cards to be handled and sensed by dataprocessing equipment has become a matter of increasing interest, and theuse of carbon paper sheets or typewriter ribbons as the medium forplacing spots of the required properties has been suggested, one suchsuggestion appearing in the patent to Mumma, No. 2,744,031.

It has been found, however, that most of the pressure transfer layers,as currently prepared, are lacking in certain respects when an attemptis made to adapt them to data processing use. While the marks made areof adequately permanent nature considered in the sense of ordinarycarbon copy use and will remain sufficiently legible under mostconditions, it has been found that there is a slight tendency to smudgeand spread if the marked sheet is handled a great deal, or used with theordinary sheet or card feeding and handling equipment encountered indata processing machinery. Also, in conventional practices, it isdifiic'ult to control the smudging of the copy sheets or cards in thetransfer process due to the dirty surface of the transfer sheets. Whenthis smudging occurs, the reliability with which the true mark can beautomatically sensed is severely impaired, even though the impairment issometimes comparatively slight by visual standards, and falseindications are picked up due to contact of the dirty, uncoated surfaceof the transfer sheet with the record caused by handling during thetransfer process.

The objects of the present invention are to provide a transfer elementwhich is smudge-free and clean to the touch, has excellent adhesion,even for greasy surfaces, and is of such character that the transferredspot or image when formed will be substantially proof against smudgingand such that the marked card or sheet will pass readily throughordinary handling equipment without the spots sustaining any changesufficient to affect the accuracy of the sensing operation.

It is a feature of the present invention that the foregoing objects arebrought about by constructing the transfer sheet with a coating havingat least two distinct layers or strata, simultaneously transferable fromthe carrier sheet in a substantially stenciling fashion, in which boththe bottom stratum or layer nearest the carrier sheet and the top layerhave smudge-resistant properties. These properties of smudge-resistanceare due to the absence from the top layer of material to which thesensing device will react, so that even though the top layer ispartially displaced by handling, the displaced portion will not affectthe sensing means, or to the char! acter of the bottom layer as beingrelatively hard and ice of low adhesiveness so that, even though chargedwith a type of material to which the sensing device in question willreact, it is not subject to ready displacement from the spot whereapplied.

By reason of the placement of the bottom smudgeresistant layer adjacentthe carrier sheet, the image formed when the coating is transferred bypressure from the carbon paper to the copy sheet has an exposed surfacewhich normal contact with handling devices does not seriously affect, sothat, even though the sheet has been fed and handled, there is assured areaction at the sensing means which is the same as that which the spotwould have brought about in its freshly-transferred condition.

It will be readily appreciated that the principles of the invention canbe applied whether the transfer layers are arranged to deposit spotssuitable for sensing visually or by photoelectric means, by magneticmeans, by electrical contact means, or by any other means sensitive tospecial material in the coating. Examples of various types will appearas the description proceeds.

In the drawing:

FIGURE '1 is a fragmentary diagrammatic section to an enlarged scale ofa pressure-sensitive transfer element according to one form of theinvention.

FIG. 2 is a fragmentary diagrammatic section to an enlarged scale of acopy sheet having thereon a spot formed by transfer from the element ofFIG. 1.

Referring to the drawing, the transfer element of the present inventioncomprises a carrier sheet or strip 11 of paper, regenerated cellulose,cellulose acetate, or a' similar thin, flexible material. Onone surfaceof the sheet or strip 11 is formed a transfer coating 13 which ischaracterized particularly by the fact that it is made up of two strataor layers 15 and 17. The base layer 15 which lies next to the carrier 11and the top layer 17 are both layers of material having smudge-resistantproperties as hereinbe-fore mentioned and defined. The base layer hasplaced on its surface the top layer 17 which is so constituted as tofirmly bond to the base layer 15. The layers 15 and 17 are somewhatcommingled adjacent their meeting surfaces to effect this bond, asindicated by the character of the cross-hatching in FIG. 1. The natureof the composite layer 15, 17, Le. the coating 13, is such that when thecarrier 11 is impressed by a stylus or struck by a type, substantiallyall of the material of coating 13 in the area pressed or struck will betransferred to an adjacent copy sheet, leaving little, if any on thetransfer carrier. In other words. the coating has the property known inthe art as stenciling. The dual character of the coating 13 lends itselfvery well to this purpose since the layer 15 as formulated is relativelyhard and has a particularly low degree of adhesiveness for the carrier11 to promote ready release under pressure without division of thecoating, and the layer 17 is formulated to have a more pronouncedadhesiveness for the copy paper or receiving sheet normally used wherebyto bring about the stenciling transfer. While, in most cases, it ispreferable to have the layer 15 separate from the foundation 11 almostentirely, this is not always essential, and the term stenciling isunderstood to include cases where only a portion of layer 15 may betransferred, so long as it is sufficient to be effective for thepurposes intended.

The FIG. 1 form is at present found most useful in systems employingvisual reading, or for automatic photoelectric or magnetic sensing. Forvisual use or for photoelectric sensing a pigment having lightreflecting or absorption value is carried in the bottom layer 15, andthe same would be so colored as to contrast sharply with the color ofthe cards or copy sheets on which it is to be used. Carbon black, forexample, would serve 'elfeetively if used on light colored cards. In oneembodiment of the present invention the layer 17 is compounded withlittle or no pigment so as to be substantially transparent. Anotherembodiment of the present invention comprises the addition of a tintcolor to the top layer 17 which together with the dark pigment of thebottom layer 15 gives an overall lightened color to the transfer paper.However, on transference the colors apparently coalesce under pressureand the tone of the stronger pigment of layer 15 is emphasized yieldinga stronger colored copy than would have been expected from the lightappearance of the transfer sheet. Here, for instance, a blue pigment ora pink pigment may be included in the layer 17 and a black or red colorin layer 15, respectively. The final transfer paper then has a lightcolored appearance, but upon transfer under pressure the dark black orred copy predominates to give a strong colored copy.

When the pressure transfer has been effected in the normal way, aproduct as seen in FIG. 2 will result, having an image 23, the bottomlayer 17a, previously the top layer of the transfer sheet, lies againstand is adhered to a copy sheet 21, and the top layer 15a, which waspreviously the bottom layer of the transfer sheet, is exposed at thesurface. It will be seen that the layer 15a is bonded by the adhesivelayer 17a effectively to the copy sheet. Layer 15a is itself not softenough to be disturbed or spread by random contact with feeding orhandling devices, or so hard as to be substantially impervious to suchspreading, and the layer 17a remains in its original position preciselyas placed. Because the layer 15a is hard enough to resist displacement,it is clearly compounded to be smudgeresistant as the term is definedabove and used throughout this description.

Included in the term pigment, of course, are pulverulent materials ofall kinds whether used for their light response or not. In case thepigment is of magnetic particles, iron oxide for example, the image ormark 23 will be capable of being sensed by magnetic pick-up means, andin this instance the layer 17a may also be pigmented with a tint colorif desired, so long as the pigment used is non-magnetic.

FIG. 1 illustrates a form of the invention in which a carrier sheet 11carries a coating 13 including a 'base layer 15 and a top layer 17. Thebase layer 15 is so constituted that if and when exposed to normalabrasion and rubbing it will not be displaced or spread. This means thatthe mixture is compounded to be relatively hard and, in the dry state,to have a low degree of tackiness or of adhesiveness for most othersurfaces. When applied, it is rendered fluid by reason of heat or avolatile liquid dispersion medium, so that in drying and setting eitherby cooling or evaporation it attaches itself to the carrier sheet withtenacity sufiicient for ordinary purposes, and will readily releasetherefrom. The base layer 15 includes a pigment intermixed therewith,which may be of the types heretofore mentioned which are sensed withlight-responsive or magnetic means. In addition, in this form a properlycompounded coating which includes electroconductive pigmentary material,e.g. silver powder, aluminum powder, or finely divided graphite, may beused to actuate eventuallyan electric sensing means, e.g. by closing acircuit between feeler brushes.

Inasmuch as the layer 15 is prepared so as to be hard and normally tohave low adhesiveness for other surfaces, it will not ordinarilytransfer particularly well by itself under most conditions. The toplayer 17 is applied thereover and is so compounded as to be somewhatsofter and more adhesive than the layer 15. It will be thoroughlyconnected, to layer 15 in the manner heretofore explained and willprovide a surface having sufi'lcient adhesiveness to cause localpressure transfer to a receiving copy sheet, taking theadjacent portionof layer 15 with it. It is largely immaterial whether layer 17 haspigment or not, but pigment may be included for the purpose of maskingor 4 intensifying the ffect of the pigment used in the layer 15 ifdesired.

When pressure transfer has been effected in the normal way, a product asseen in FIG. 2 will result, having an image or mark 23, the pigmentedlayer 15a of which is on the exposed surface. This layer, however, is ofsuch a hard, non-adhesive character that it will resist normal abrasionor contact displacement, and hence is smudgeresistant, even thoughcontaining the pigment to be sensed. The layer 17a next to the copysheet firmly anchors the entire mark 23 in place.

If the pigment used to prepare the layer 15 is electroconductive, thelayer is also preferably compounded using ingredients which will renderthe particles mutually contacting so that a continuing conductiverelationship extends throughout the layer. Illustrative examples ofmixtures suited to this purpose are as follows:

(Formula 1) Base layer:

Examples of mixtures suitable for preparing a transfer sheet inaccordance with FIG. I are as follows:

EXAMPLE I Base layer: Formula 1 or 2 as given above. (Formula 3) Toplayer:

Ingredients Parts by weight Carnauba wax 45 .0 Indopol H-300 (Tackyviscous liquid mixture of polymerized butene isomers) Beeswax 6.0Mineral oil 20.0 Pigment, if desired 10.0 to 20.0

Example I represents a coating for producing spots 23 especialy forsensing by electrical contact means.

EXAMPLE II (Formula 4) Base layer:

Ingredients- Parts by weight Carnauba wax 45.0 Ceresin 4.0 Lanolin 6.0Mineral oil 15.0 Carbon black 12.0

Top layer: Formula 3 as given above.

Example II represents a coating for producing spots 23 especially forsensing by light-sensitive means.

EXAMPLE III (Formula 5) Base layer:

Ingredients- Parts by weight Carnauba Wax 45.0 Ceresin 4.0 Lanolin 6.0Mineral oil 15.0 Magnetic iron oxide 18.0

Top layer: Formula 3 as given above. Example III represents a coatingfor producing spots 23 especially for sensing by magnetic means.

The coatings of Examples 1 to III are formulated for use particularly inconnection with carrier sheets of carbonizing kraft, but the base layerformulation may be suitably varied as previously indicated to providefor use with carrier sheets of a smooth film if desired.

It will be understood that the examples given above are illustrativeonly and that various types of formulations may be employed within thescope of the present invention. For example, the compositions for thevarious layers may be compounded as resinous base mixtures renderedfluid for coating by being suspended in volatile solvent. liquids asshown in copending application Serial No. 503,830, filed April 25, 1955,and now abandoned, and in US. Patents No. 2,872,340 issued February 3,1959, and No. 2,810,661 issued October 22, 1957. In this connection itshould be pointed out that, in general, the layers cast from a mixtureof a resinous base sus pended in volatile solvent, when properlycompounded, perform especially well as the layer 15 which is designed tobe resistant to mechanical spreading or displacement. Among thetackifying synthetic resinous adhesives which may be substituted for thepolymerized butene mixture in Formula 3 supra are known adhesives suchas plasticized polyvinyl chloride, plasticized polyvinyl chloridevinylacetate copolymers, vinyl ethers such as polyvinyl methyl ether andpolyvinyl isobutyl ether, polyvinyl alcohol, and the butadiene rubbercopolymcrs such as of styrene and acrylonitrile (Buna N and Hycar OR),as well as others.

Integration of the layers at the interface may be effected by varioussuitable treatments, such as the softening of the surface of the baselayer by solvent treatment just prior to depositing the top layer, orpreferably by subjecting the coated sheet to controlled heating orfusion just after the top layer has been placed.

From the foregoing description it can be seen that a novel coated,smudge-proof, clean handling, pressure-sensitive transfer element of thecarbon paper type has been provided in which the coating comprises abase layer and a top layer which are simultaneously transferable instenciling fashion from the carrier to an adjacent copy sheet, and inwhich the base layer 15, by virtue of its properties of hardness andresistance to mechanical displacement, is thoroughly smudge-resistant. Atransfer element of this character is capable of producing novel imagesand spots in which the transfer sheet layers are inverted and which haveexcellent properties of adhesion, even for greasy or dirty surfaces, andaccordingly have a high degree of resistance to smudging so as toperform reliably in data processing equipment in spite of the feedingand handling to which they will normally be subjected prior to sensing.Thus, in the case of the processing of checks or receipts which aregreasy or oily due to being handled and carried by factory Workers ormechanics, etc., the transfer papers of the instant invention furnishexcellent properties of adhesion for the greasy surfaces and insure thatthe images transferred will not flake ofl.

The term sheet as used herein applies to flexible foundation membranesof any sort in coated or uncoated condition, whether of limited lengthor of extended length, and in this connection includes items sometimesreferred to as webs, strips, or ribbons.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

We claim:

1. As a new article of manufacture, smudge-resistant pressure-senstivetransfer element of the carbon paper type comprising a flexiblefoundation sheet having thereon two mutually adhering layers which aresimultaneously locally transferable from the foundation to a copy sheetin a substantially stenciling manner in response to a blow or pressure,the base layer adjacent the surface of the sheet having readilyreleasable contact therewith and being so compounded as to be relativelyhard and to have low adhesive properties whereby to resist stronglydisplacement due to normal physical contact with other articles, andbeing charged with pigment designed for automatic sensing, and the toplayer being integrated with the surface of the base layer and havingadhesive properties both for a copy sheet surface and for said baselayer to effect local transfer thereof when desired.

2. As a new article of manufacture, a smudge-resistantpressure-sensitive transfer element of the carbon paper type comprisinga flexible foundation sheet having thereon two mutually adhering layerswhich are simultaneously locally transferable from the foundation to acopy sheet in a substantially stenciling manner in response to a blow orpressure, the base layer adjacent the surface of the sheet havingreadily releasable contact therewith and including a pigment designedfor automatic sensing, and being sufliciently tenacious and free fromadhesiveness to be normally, of itself, non-transferable under a blow orpressure, and the top layer being integrated with the surface of thebase layer and being of tacky, adhesive, smudge-resistant characterwhereby to provide for local transfer of said base layer and carry thesame with it at the time of its own transfer.

3. A record-carrying element for use with automatic sensing equipmentcomprising a foundation sheet, and a local sensible carbon paper markthereon containing two mutually adhering layers, the one lying farthestfrom the foundation being so compounded as to be relatively hard and tohave low adhesive properties and transfer properties, of itself, wherebyto resist strongly displacement due to normal physical contact withother articles, and being charged with pigment designed for automaticsensing, and the other layer nearest the foundation being integratedwith the surface of the one layer and having adhesive properties bothfor the foundation and said one layer whereby said one layer istransferred and securely afiixed to said foundation.

4. A record-carrying element as defined by claim 3 in which the pigmentis magnetic pigment.

5. A record-carrying element as defined by claim 3 in which the pigmentis electroconductive pigment.

6. A record-carrying element as defined by claim 3 in which the pigmentis photoelectrically sensitive pigment.

7. A record-carrying element for use with automatic sensing equipmentcomprising a foundation sheet, and a local sensible carbon paper markthereon containing two mutually adhering layers, the one farthest fromthe foundation including a pigment designed for automatic sensing, andbeing suificiently tenacious and free from adhesiveness to be normally,of itself, non-transferable under a blow or pressure, the other layerlying nearest the foundation being integrated with the surface of theone layer and being relatively soft and adhesive and therefore subjectto possible displacement, but providing for transfer to said foundationof said one layer and carrying the same with it at the time of its owntransfer.

8. The method of preparing smudge-resistant pressuresensitive transferelements of the carbon paper type which comprises coating a flexiblefoundation sheet with a base layer containing a pigment designed forautomatic sensing, said base layer being so compounded as to berelatively hard and to have low adhesive properties whereby to resiststrongly displacement due to normal physical contact with otherarticles, applying to the surface of said base layer a top layer havingadhesive properties both for a copy sheet surface and for said baselayer, and integrating said layers so that upon transfer ,to a copysheet said top layer will carry said base layer with it.

9. The method of claim 8 in which integration of the layers is elfectedby treating the base layer with a solvent prior to applying the toplayer.

10. The method of claim 8 inwhich integration of the layers is effectedby subjecting the coated sheet to controlled heating after the top layerhas been applied.

11. The method of preparing smudge-resistant pressure-sensitive transferelements of the carbon paper type which comprises coating a flexiblefoundation sheet with a base layer containing pigment designed forautomatic sensing, said base layer being suificiently tenacious and freefrom adhesiveness to be normally, of itself, nontransferable under ablow or pressure, coating said base layer with a top layer having tacky,adhesive, smudge-resistant properties, and integrating said layerswhereby to provide a transfer element in which the top layer ispressure-transferable and carries with it at the time of its transfersaid normally non-transferable base layer.

12. The method of claim 11 in which integration of the layers isefiected by treating the base layer with a solvent prior to applying thetop layer.

13. The method of claim 11 in which integration of the layers isefiected by subjecting the coated sheet to controlled heating after thetop layer has been applied.

References Cited in the file of this patent UNITED STATES PATENTS2,188,590 Bjorksten et a1 Jan. 30, 1940 2,744,031 Mumrna May 1, 19562,762,715 Newman Sept. 11, 1956 2,912,344 Newman et al Nov. 10, 1959

1. AS A NEW ARTICLE OF MANUFACTURE, SMUDGE-RESISTANT PRESSURE-SENSITIVETRANSFER ELEMENT OFTHE CARBON PAPER TYPE CONPRISING A FLEXIBLEFOUNDATION SHEET HAVING THEREON TWO MUTUALLY ADHERING LAYERS WHICH ARESIMULTANEOUS LOCALLY TRANSFERBLE FROM THE FOUNDATION TO A COPY SHEET INA SUBSTANTIALLY STENCILING MANNER IN RESPONSE TO A BLOW OR PRESSURE, THEBASE LAYER ADJACENT THE SURFACE OF THE SHEET HAVING READILY RELEASABLECONTACT THEREWITH AND BEING SO COMPOUNDED AS TO BE RELATIVELY HARD ANDTO HAVE LOW ADHESIVE PROPERTIES WHEREBY TO RESIST STRONGLY DISPLACEMENTDUE TO NORMAL PHYSICAL CONTACT WITH OTHER ARTICLES, AND BEING CHERGEDWITH PIGMENT DESIGNED FOR AUTOMATIC SENSING, AND THE TOP LAYER BEINGINTEGRATED WITH SURFACE OF THE BASE LAYER AND HAVING ADHESIVE PROPERTIESBOTH FOR A COPY SHEET SURFACE AND FOR SAID BASE LAYER TO EFFECT LOCALTRANSFER THEREOF WHEN DESIRED.